Variable speed transmission



od. 19, 1937. y, H. G. KE'LL'ER 2,096,431

VARIABLE SPEED TRANSMISSION Oct. 19, 1937. H. G. KELLER VARIABLE SPEED TRANSMISSION 2 Sheets-Sheet 2 Filed Feb. 9, 1954 YD/'em Jn 175 Il .r

- y Zj'eZZer Patented Oet. 19, 1937 UNITED .STATES PATENT OFFICE Belt Company, Chicago, lll., a Illinois onof Applieeuen February s, 1934, serian Ne. 110.401 s claim.. (cLn-zsarz) This invention relates to a variable speed transmission. In the particular form shown the transmission includes two pairs of pulleys and means for moving them toward and from each other.

A exible chain or belt is used and engages both pairs of pulleys. As the pulleys are moved toward and from each other. their effective diameter is varied. In transmissions of this general type it has heretoforev been necessary to provide a belt tightener to take up slack in the belt and in general to provide against unsatisfactory looseness in the belt.

One of the objects of the present invention is to provide means for taking up the slack without l5 the necessity of a belt tightener. Another-object keep the chain adjusted at all times and for all positions of the pulleys. Another object is to pro- 20 vide in connection with such a transmission chain adjuster means to permit the occurrence of slip due to excessive overload. V r

Other objects will appear from time to time in the specification .and claims.

The invention is illustrated more or less diagrammatically in the accompanying drawings, whereinz- Figure A1 is a horizontal, longitudinal cross section, \,.`th some parts in elevation, showing one 30 form of transmission;

Figure 2 is a vertical longitudinal section of 1 1, withthe casing, taken at line 2 2 of Figure some parts shown in elevation;

Figure 3fis a view generally similar to Figure l,

3'5 showing a modified form;

VFigure 4 is a longitudinal vertical sectional view, taken atline 4-4 of Figure 3.

Like parts aredesignated .by like characters throughout the speoication vand drawings.

Any suitable form of casing may be used. It-is preferable to use a liquid 'tight casing and to have the transmission run in oil or other lubricant.

In the form here shown, the casing includes a 45 lower portion A having a flange A1 laterally extended and providing means for attaching the upper portion Az of the housing, which upper portion is preferably provided with a flange A", to contact the flange A1. The flanges are perfo- 5() rated at suitable points to receive screws or other ing As which is closed by a cover plate, A'1 held 55 in place by screws or other fastening means A".

' 'I'he housing portionsk are shaped to receive a shaft B1 is provided with a key B4 which fastens a pair of inclined faced or generally conical pulleys to the shaft B. Each of these pulleys is provided with a shaft engaging and surrounding portion Bs slidably mounted on the shaft and a chain engaging portion Bc which, as shown, is preferably provided with an inclined and generally conical working face B". Antifrictionbearings B are, mounted about the cylindrical portions B, of the pulleys and bear partially against the portions B1.

'I'he housing members are arranged to receive a pair of antifriction bearings C, C, within which a shaft C1 is mounted for rotation. C1 is a cover plate and C" is a packing plate arranged to prevent leakage of lubrication. A key. C4' is provided on the shaft C1 to receive a pair of pulleys generally similar to the pulleys B". Each of them is provided with a cylindrical portion C which engages the key C* and is slidable upon the shaft C1. '111e pulleys are also provided with portions C each of which is provided with an inclined or conical working face C". Antifriction bearings Cs are mounted about the cylindrical portions Cl of the pulleys and in part bear against the portions C. e l

In the form shown in Figures land 2, means are provided for moving th pulleys of each pair toward and from each oth r and this means is so arranged that as the pulleys of one pair move together the pulleys of the other pair move apart. 'I'he pulley adjusting means includes an adjusting shaft D, journaled in suitable bearings in the housing and provided with a handle or operating member D1. The shaft is provided with two oppositely threaded portions D2 and D1, upon each of which is threaded a lever support D4. Mounted at each end of each member D4 are arms Dls of composite pulley adjusting levers. These arms are engaged upon studs or rounded portions Ds ofthe member D4 The composite levers are fulcrumed upon supports D" provided at each end with studs or rounded portions D. The supports D"r are received uponI a shaft Dg which is provided with oppositely threaded portions D10 and D11 and is mounted in suitable bearings in the housings. The shaft D is provided with a nut or angularly shaped portion D12 by means of which it maybe rotated to adjust the position of the fulcrum members D". Spacing members D11, D1" are providedl between the lever members D's and preferably on either side of the fulcrum member D". The lever members D5 are fastened are perforated or otherwise shaped to receive pair of antifriction bearings;'B, B. A shaft =B1 is supported inv these bearings. Bz is a cover plate y and B" is a packing plate arranged about the oo shaft B1 to prevent leakage of` lubricant., The.

lap porabnpf the cylindrical sections cs or the poneys o6. Within each of the cups E1 and bearing against the outer member of one of the antifriction bearings C8 are coil springs E2. Inter- 'mediate the members D4 and D7 the lever portions D5 are perforated to receive studs or projections E3, two of which are formed on each of two collars E1 which surround the shaft B1, portions of the cylindrical pulley sections B5, each of which bears against the 'outer member of one of the antifriction bearings B5. The collars E4 may be provided with laterally extending flanges E5 to increase their area of contact with the bearing members B5.

In the form shown in Figures 3 and 4, the composite lever acts only upon one pair of pulleys. The other pair is held by springs and is moved iny and out by the belt and not directly by'anyy lever or any positive adjustment. The arr-angement of shafts and pulleys upon them is the same vin the two forms of the invention. In the form shown in Figures 3 and 4, F, F are coil springs positioned about the cylindrical sections C5 and bearing against the pulleys C5. At their opposite ends the springs bear against plates F1 mounted about the shaft C1. The plates are held in place by split rings FZ which are fitted into grooves or notches F5 cut in the shaft C1. 1

The positive adjusting means of the form shown in Figures 3 and 4 is substantially onehalf of that shown in Figures l and 2. It is as though the lever members D5 had been cut offto the right of the fulcrum members D". There is thus upon each of the threaded sections of the shaft D a member D4 provided at its upper ends with studs D5 to receive the lever sections D5. The lever sections are fulcrumed upon members D7 one of which is threaded upon each of the threaded portions D10 and D11 of the shaft D9.

The members D5 are perforated to receive the studs E3 of the collars E4. Since, however, the lever members D5 do not extend appreciably beyond the fulcrum member D7 the levers are spaced and fastened together intermediate their ends by members G, G, which are positioned between the lever members D5 and one oneach side of the shaft B1 and fastened to the members D5 by screws G1. The arrangement of collars and bearings for contacting and moving the pulleys B5 is the same as in the form shown in the earlier figures and need not again be described.

Many different forms of driving chain or belt may be used. As shown herewith, H isachain whichmay be formed of links H1 within which may be seated pulley contacting members H2. The particular details of the chain need not be shown in full as they form no essential partA of the present invention.

' While I have herewith shown and described a practical operative device, nevertheless many changes might be made in the size, shape, number and disposition of parts Without departing from the spirit of my invention and I wish, therefore, that my showingibe taken asin a sense dia` grammatic.

The usevand operation of my invention are as follows:

In general, the transmission is" to be used to give a variable speed' in a power transmission.

' One shaft, for example, the shaft B1, is a driving speed, the shaft D is rotated by the handle D1 and because the threaded portions of the shaft D are oppositely threaded, when the shaft is rotated one composite lever will move in one direction and the other composite lever will move in the opposite direction, so that one direction of rotation of the shaft D moves the levers apart and the opposite direction of rotation moves them together. In the form shown in Figures 1 and 2, since both pairs of pulleys are engaged by the levers, as one pair is moved outward the other is moved, inward and vice versa. In the form shown in Figures 3 and 4, only one pair is moved positively, but the other pair accomplishes a corresponding and compensating movement which is permitted by the springs F. These springs tend normally to move the pulleys C5, C5 toward each other as far as possible, but permit the pulleys to be forced apart by the chain and thus permit compensating and corresponding movement in and out, when the pulleys B5 are positively moved by the adjustment shown.

It will be seen that in both forms of the invention one pair of pulleys is provided with a yielding mounting in the form of compression springs which bear on each of the pulleys of the pair in question and serve automatically to keep the chain in proper adjustment. The springs force the pulleys inwardly and thus take up slack which might otherwise occur in the chain as the result of adjustment of the pulleys toward and from each other. In the form shown in Figures l y and 2, where the pulleys of both pairs are adjusted positively toward and from each other, the springs are effective upon a single pair and force them inwardly always as far as possible and thus take up the slack. In the form shown in Figures enY 3 and 4, Where one pair of` pulleys is not posiyside bending Vor movement out of alignment and consequently itis important to preserve proper alignment so that irrespective of the various positions of adjustment the chain remains as nearly v as possible on the same'central line. For that reason, evenl in the pulleys which .are urged inwardly by springs, the arrangement is such as to preserve the balance and alignment and consequently both pulleys of the right hand pair in the two forms of the invention are providedv with springs which are of the same size and power and are, therefore, balanced as to their action so that the force urging each pulley toward the center is the same and is balanced at all times. 'I'herefore the springs have no unbalancing eifect and cannot move the pulleys out of alignment. Consequently they cause no distortion and put no added side wear or misaligning forces on the chain. d

'I'he device ofthe present invention is so designed as to provide positive drive, up to a desired overload capacity, and to provide a slip drive beyond that. If the force is sufficient on the chain, the springs will permit some slip. This action is not beneficial to the chain but it con' stitutes a safety feature so that each unit thus in effect becomes its own "safety valve and slippage will occur when breakage would otherwise have occurred.

I claim:

1. In a variable speed transmission, a driving shaft and a driven shaft, a pair of pulleys slidably mounted on each shaft, and unit means for simultaneously and oppositely adjusting the pulleys of each pair toward and from each other, a flexible transmission member positioned about said pulleys, lying between the pulleys of each pair and engaged by the working faces of said pulleys, one pair of pulleys provided with balanced springs positioned one between each of said pulleys and said unit adjusting means, and effective to force the pulleys of that pair equally toward each other to the limit permitted by said flexible transmission member, said springs carrying the entire -axial thrust of said pulleys the springs being effective to maintain the said ilexible transmission member on a constant center.

2. In a variable speed transmission, a driving shaft and a driven shaft, a pair of pulleys having inclined working faces and being slidably mounted on each shaft, and unit means for simultaneously and oppositely adjusting the pulleys of each pair toward and from each other, a exible transmission member positioned about said pulleys, lying between the pulleys of each pair and engaged by the Working faces of said pulleys, one pair of pulleys provided with balanced springs positioned one between each of said pulleys and said unit adjusting means, and effective to force the pulleys of that pair equally toward each other to the limit permitted by said flexible transmission member, said springs carrying the entireaxial thrust of saidpulleys the springs being effective to maintain the said flexible transmission member on a constant center.

3. In a variable speed transmission, a driving shaft and a driven shaft, a pair of pulleys having inclined working faces and being slidably mounted v on each shaft, and unit means for simultaneously and oppositely adjusting the pulleys of each pair toward and from each other, a flexible transmission member positioned about said pulleys, lying between the pulleys of each pair and engaged by the working faces of said pulleys, one pair of pulleys provided with balanced springs positioned one between each of said pulleys and said unit adjusting means, and effective to force the pulleys of that pair uniformly and constantly toward each other to the limit permitted by said flexible transmission member, said springs carrying the entire axial thrust of said pulleys the springs being effective to maintain the said flexible transmission member on a constant center.

4. In combination ina variable speed transmission, a driving shaft and a driven shaft, a pair of cooperating, oppositely faced pulleys having inclined working surfaces, slidably mounted on each shaft, a flexible transmission member engaging the pulleys of both pairs and transmitting power fromone pair to the other, means for adjusting the relative position of the pulleys of each pair toward and from each other, said means simultaneously and oppositely effective upon each pair, and balanced yielding means effective upon the pulleys of one pair to move them equally toward each other to the maximum limit permitted by said flexible transmission member, whereby the movement of said pulleys towards each other acts to take up slack in said flexible transmission member, lsaid yielding means carrying the entire axial thrust of said pulleys and whereby the said flexible transmission is maintained on a constant center.

5. In combination in a variable speed transmission, a. driving shaft and a driven shaft, a pair of cooperating, oppositely faced pulleys having inclined working surfaces, slidably mounted on each shaft, a flexible transmission membervengaging the pulleys of both pairs and transmitting power from one pair to the other, means for adjusting the relative position of the pulleys of each pair toward and from each other, said means simultaneously and oppositely effective upon each pair, and balanced, yielding spring means positioned one between each of said pulleys and said unit adjusting means, and effective upon the pulleys of one pair to move them constantly and uniformly toward each other to the maximum limit permitted by said flexible transmission member to maintain said flexible transmission member on a constant center, whereby the movement of said pulleys towards each other acts to take up slack in said flexible transmission member said spring means carrying the entire laxial thrust of said pulleys.

6. In a variable speed transmission, a driving shaft and a. driven shaft, a pair of pulleys slid- -ably mounted on each shaft, and simultaneous manually controlled balanced means for adjusting the pulleys of one pair toward and the pulleys of the other pair away from each other, a flexible transmission member positioned about said pulleys, lying between the pulleys of each pair and engaged by the working faces of said pulleys, one pair bf pulleys provided with balanced springs positioned one between each of said pulleys and said unit adjusting means, and effective to force the pulleys of that pair equally toward each other to the limit permitted by said flexible transmission member.

7. In a variable speed transmission, a driving shaft and a driven shaft, a pair of pulleys slidably mounted on each shaft, and simultaneous balanced lever means for adjusting the pulleys of one pair toward and the pulleys of the other pair away from each other, a flexible transmission member positioned about said pulleys, lying between the pulleys of each pair and engaged by the working faces of said pulleys, one pair of pulleys provided with balanoedsprings positioned one between each of said pulleys and said unit adjusting means, and effective to force the pulleys of that pair equally toward each other to the limit permitted by said flexible transmission member and to maintain said flexible transmission member on a constant center.

8. In a variable speed transmission, a driving shaft and a driven shaft, a pair of pulleys slidably mounted on each shaft, and simultaneous balanced lever means for adjusting the pulleys of one pair toward and the pulleys of the other pair away from each other, said means supported upon the housing at two diametrically opposite points intermediate the ends of the housing, a flexible to the limit permitted by said flexible transmission member and to maintain said flexible transmission member on a constant center.

HENRY G. KELLER. 

